/Engine/Source/Runtime/SlateCore/Public/Types/SlateAttribute.h
Not all invalidation is supported by SlateAttribute. ChildOrder: The update of SlateAttribute is done in the SlatePrepass. We can't add or remove children in SlatePrepass. AttributeRegistration: In FastPath, the SlateAttribute are updated in a loop. The iterator can't be modified while we are looping.
template<typename T> static constexpr bool IsInvalidateWidgetReasonSupported ( T Reason )